1. The Field of the Invention
The present invention relates to portable furniture and, more particularly, to novel systems and methods for providing comfortable, compact, inexpensive, and lightweight seating for easy transportation and storage.
2. The Relevant Technology
Throughout history, people have sought more comfortable seating arrangements. Chairs, stools, and the like allow people to relieve stress on the legs and feet, while remaining alert and performing tasks that do not require a great deal of motion. In the twentieth century, folding chairs have made it possible for people to keep a space clear when necessary, and to erect suitable seating for gatherings or special events. However, current folding chairs possess a number of drawbacks.
For example, folding chairs are often somewhat heavy. The chair must reliably support the weight of even a fairly large person. The bending stress on any member is proportional to the length of the member multiplied by the force acting upon it. Therefore, the length of the seat effectively multiplies the forces tending to bend or break the seat. Typically, seats for folding chairs have been made from stronger (and heavier) materials, such as steel, to overcome the effect of these bending stresses. The resulting chairs are heavier and therefore cost more to ship, and require more effort to move, fold, and unfold.
Thus, it is desirable to use lightweight materials such as plastics to reduce the weight of folding chairs. However, many known folding chairs, especially those that incorporate lightweight materials, do not stand up to repetitive use. Groups such as the Business and Institutional Furniture Manufacturers' Association (B.I.F.M.A.) have set up standards for portable furniture. Such standards typically require that portable chairs be designed to receive a given weight loading to simulate use for a specified number of cycles, often on the order of 100,000. Many known folding chairs bend or break after only a few thousand cycles, and therefore can be expected to have a relatively short useful life.
Certain known chairs use metal to reinforce lightweight materials. The seat may, for example, be supported by a frame encircling the seat or by metal rods threaded through the lightweight material. In addition to increasing the weight of the folding chair, such reinforcing measures add to manufacturing time because the supporting structure must be properly aligned with the seat, and possibly with the legs as well.
In general, many known folding chairs are somewhat expensive to produce because the manner in which they are assembled requires the use of a great deal of manual labor. The legs must often be properly aligned with the seat so that mechanical fasteners can be attached to the legs and the seat. If metal supporting parts are to be threaded through the lightweight seat member to connect the legs, the lightweight seat member may have to be aligned with each leg assembly so that the threading operation can be carried out. Often, the various fasteners involved must be installed at locations that are not easily accessible for machinery. Thus, the fasteners must often be installed by hand.
Accordingly, a need exists for a portable, folding chair that is lightweight and comfortable, and yet folds to a thin, stackable configuration. Such a chair must safely support the weight of a fairly heavy person. In addition, the chair should be inexpensive to produce in large quantities with a minimum of parts and assembly.